Process of making printing blocks



K. SCHLECHT.

PROCESS 0F MAKING PRINTING BLOCKS.

APPLICATION FILED Nov. I4. 1914.

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ATTORNEY .KABLCHLECHl 0F BBLINGE'N, GERMANY.

PROCESS 0F MAKING PRINTING BLOCKS.

Specification of Letters Patent. Patented Apr. 11, 11922.

Application led November 14, 1914. Serial No. 872,129.

(GRANTED UNDER-THE PROVISIONS 0F THE ACT 0F MARCH 1921, 41 STAT. V12.,1313.)

To all whom it may concern.'

Be it known that I, KARL SCHLECHT, a citizen of the German Empire,residing at Bblin en, in the Kingdom of Wurttemberg, mpire of Germany,have invented certain new and useful -Improvements in Processes ofMaking Printing Blocks, of which the following is a specification.

This invention relates to the process of making printing blocks bylaying on the spots cleared by the development of a chromate colloidcopy, a bed of resin or varnish capable of resistin the action of fatsand acids, and has for its object the production of a block having auniform surface which will be more advantageous and economical for usein both direct and offset printing, and by means of which a large numberof and particularly effective, impressions may be obtained.

In the process of making printing blocks by laying on the spots clearedby the development of a chromate colloid copy, a bed of resin or varnishcapable of resisting the action of fats and acids, it has been foundthat the picture elements, consisting of a layer of resin or varnish,project a little higher than the remaining parts of the printing block.IThis is especially disadvantageous for offset printing because the blockwears unevenly, so that the number of clear impressions that can beobtained, is very limited, and the india rubber cloth of lthe offsetpress is worn out rapidly by repeated contact with the uneven surface.The picture elements bein exposed, they wear off very quickly andinstead of producing a fine grain and clear impressions, a coarse grainand blurred impression or picture, results.

My method of making these printing blocks is such that blocks areproduced which have a substantially uniform printing surface, so thatthe number of impressions that may be obtained is greatly increased; andthe india rubber cloth is not injured by the Hat surface, so that wearis materially reduced.

I will describe one process embodying my invention and will then pointout the novel features thereof in claims:

The accompanying drawing illustrates somewhat diagrammatically, apreferred embodiment of my invention.

F 2 is a view showing the plate after etching.

Fig. 3l is a View showing the plate after v coating with resin orvarnish.

Fig. 4 is a view showing the plate after treatlng with turpentine.

Fig. 5 is a view showing the plate after recoating with greasy inkalone. v

Fig. 6 is a view showing the plate after treatment with nitric acid.

In all of the views, the sequence in which the ingredients are appliedand removed are indicated by the accompanying legends.

In carrying out the invention according to the drawing, the chromatecolloid copy or layer Kis first developed, and then rolled in withgreasy ink H and dusted with asphalt powder A as shown in Fig. 1; isthen warmed up and etched in diluted nitric acid or the like, so thatthe picture spots are reduced below the level of the rest of the plate Bas shown in Fig. 2. The plate B is now covered as shown in Fig. 3, witha solution of resin or varnish C which is insoluble in turpentine orbenzine, and is then treated with turpentine or the like by means ofwhich the greasy ink H and the covering of asphalt powder A with theresin C adhering thereto is removed, leaving the picture spots orperspective plane still coated with .the insoluble resin or varnish C asshown in Fig. 4. Due to the fact that these picture spots are depressedbelow the rest of the plate B, the solution of resin penetrating intothe spots is therefore laid on thicker than has hitherto been the case,so that these parts have a considerably increased power of resistance,when subsequently subjected to the graining and printing operation.

The graining is accomplished by rolling in the entire plate B once morewith greasy ink H as shown in Fig. 5 and then treating it with asolution of diluted nitric acid or the like, which removes the layer ofcolloid K and produces the graining upon the plate at the same time. Bythis operation the surface of the plate B is reduced somewhat so as tocorrespond with the lower level of the picture spots. In this way, afiat printing block is produced in which the design and the grain aresubstantially at the same level as shown in Fig. 6.

This feature is of the greatest importance for offset printing, as itenables a large number of clear impressions to be made, bypreventing'the sharp picture elements from being exposed and thuswearing off quickly, as distinct from the blurred and indistinctimpressions or pictures produced by coarse grain picture elements.Moreover, it is possible by varying the levels of the picture spots andthe grained surface, to make a printing block that will, particularly inoffset printing, give very effective impressions. Furthermore, if it isdesired the picture spots may be even depressed slightly below thegrained surface of the block or plate, so that the ink collects onthemin a thicker layer; it is then raised by the india rubber cloth ofthe offset press and the laying on of the ink on the paper is moreeffective than can be obtained from blocks ordinarily in use. Thismethod of making printing blocks may of-course be used for blocksintended for both offset printing and direct printing. p

Having thus described my invention, what I claim and desire to secure byLetters-Patent is:

l. The method of makingl printing blocks from developed and etchedchromate colloid plates from which the protecting colloid and resisthave not been removed, which method consists in coating the face of suchplate with a resinous material so that the etched surfaces will becomefilled to the same plane as the original surface of the block and thenremoving the protecting colloid and its overlying resist and resinouscoating.

2. The method of making printing blocks from developed and etchedchromate colloid plates from which the protecting colloid and itsoverlying resist have not been removed, the resist consisting of greasyink and asphalt powder, which method consists in coating the entiresurface'of the plate with a solution of resinous material insoluble inturpentine, treating the plate with turpentine to remove the greasy inkand asphalt powder and its overlying resinous material while leaving theetched portions coated Lampes with resinous material, graining the plateby first rolling up with greas ink and then subjecting it to the actiono nitric acid to remove the colloid layer and rain the unetchedsurfaceof the plate while the etched portions are protected by theresinous material, whereby the grained surface and the etched surfacewill be reduced to substantially the same level.

3. The method of making printing blocks from developed and etchedchromate colloid plates from which the protecting colloid and resisthave not been removed, which method consists in coating the entiresurface of the plates with a reslnous material so that the etchedsurfaces will become filled to the same plane as the original surface ofthe block, removing the resist and resinous coating overlying theprotecting colloid, and then subjecting them to the action of an acid toremove the colloid layer andl grain the unetched surface of the plateswhile the etched portions are protected by the resinous material,whereby the grained surface and the etched surface will be reduced tosubstantially the same level.

4. The method of making printing blocks from developed and etchedchromate colloid plates from which the protecting colloid and itsoverlying resist have not been removed, the resist consisting of greasyink and asphaltpowder, which method consists in coating the entiresurface of the plates with a solution of resinous material insoluble inturpentine, treating the plates with turpentine to remove the resist andits overlying resinous material while leaving the etched portions coatedwith resinous material, and then subjecting them to the action of anacid to remove the colloid la er and grain the unetched surface of theplbates while the etched portions are protected by the resinousmaterial, whereby the grained surface and the etched surface will bereduced to substantially the same level. I

In testimony whereof I aiix my signature in presence of two witnesses.

KARL SCHLECHT.

Fama Kramm.

